Electron discharge device of particular materials for stabilizing frequency and reducing magnetic field problems



FOR

Jam 1967 A. J. FIEDOR ETAL ELECTRON DISCHARGE DEVICE OF PARTICULARMATERIALS STABILIZING FREQUENCY AND REDUCING MAGNETIC FIELD PROBLEMS I5Sheets-Sheet 1 Filed Feb. 6, 1963 L n R O va S E R E W N O R T a7 0 N TE H T T V P. R A N L E 0 7 D 0 AR Jan. 10, 1967 A. J- FIEDOR ETAL32%,905 ELECTRON DISCHARGE DEVICE OF PARTICULAR MATERIALS FORSTABILIZING FREQUENCY AND REDUCING MAGNETIC FIELD PROBLEMS Filed Feb. 6,1963 3 Sheets-Sheet 2 iNVENTORS ADOLPH J. FIEDOR ROBERT G. ROCKWELL BYQM 214% ATTORNEY Jan. 10, 1967 A. J. FIEDOR ETAL 0 ELECTRON DISCHARGEDEVICE OF PARTICULAR MATERIALS FOR STABILIZING FREQUENCY AND REDUCINGMAGNETIC FIELD PROBLEMS Filed Feb. 6, 1963 I5 Sheets-Sheet 5 INVENTORSADOLPH J. FIEDOR ROBERT G. ROCKWELL ATTORNEY United States Patent()fiice ELECTRON DISCHARGE DEVICE F PARTICULAR MATERIALS FUR STABILIZINGFREQUENCY AND REDUUNG MAGNETIC FIELD PROBLEMS Adolph .l. Fiedor, PaloAlto, and Robert C. Rockwell, Menlo Park, Qaliii, assignors to VarianAssociates, Palo Alto, Calif., a corporation of California Filed Feb. 6,1963, Ser. No. 256,748 34 (llaims. (Cl. 31s--3.s

The present invention relates in general to electron discharge devicesand more particularly to temperature stable electron discharge devicessuch as klystrons, traveling-Wave tubes, magnetrons, and the like.

One of the basic criteria for the use of a particular electron dischargedevice or tube in an installation which must undergo changes inenvironmental temperature conditions, such as in an unattended radarinstallation exposed to atmospheric conditions or an airborne radarsystem or in a missile, is that the temperature coefiicient (measure offrequency change with temperature change) of the device be as low aspossible. The unit in which the electron discharge device is utilizedmay be totally useless if the temperature coeflicient of the device istoo high such that the frequency of the device and, therefore, of theunit will be too drastically changed with temperature.

In the past, a typical reflex klystron, for example, would change infrequency as much as 1,000 kilocycles per degree centigrade change intemperature. Such a variation in frequency could not be tolerated in anairborne installation or in a highly sensitive parametric amplifier inan exposed radar installation. With these older electron dischargedevices it would be necessary to liquid cool such a tube and/or maintainthe environmental conditions in which the tube was placed substantiallyconstant.

The major cause of a high temperature coefiicient for a particular tubeis the existence of thermal gradients within the tube during use. Thecause of thermal gradients has been the use in previous tubes ofmaterials having low thermal conductivity. Ideally, it would bedesirable to build the tube out of a material with a high thermalconductivity such as copper to avoid the undesirable thermal gradients.However, copper is not a rigid material and is characterized by a highthermal coefiicient of expansion. Materials which have a high thermalcoefiicient of expansion are undesirable since the sizes of resonantstructures of such materials will change with changes in environmentaltemperature conditions thereby resulting in a detuning of the device.Also, the use of a high termal expansion type of material such as copperin conjunction with more rigid materials, such as steel bodies ormagnetic materials such as iron utilized in pole pieces for such tubes,results in stresses and strains being set up in the tube due to thedifferences in thermal expansion between the unlike materials, oftenresulting in leaks at the brazed vacuum joints between the unlikematerials, or misalignment of the tubes, etc.

In order to avoid thermal detuning of a tube made of material having ahigh thermal coefiicient of expansion, electron discharge devices suchas klystrons have been built of materials with low thermal coefficientof expansion and provided with a built-in temperature compensation. Forexample, tubes have been built utilizing a body of a material with a lowthermal cofliecient of expansion and drift tube headers of a materialwith a different thermal coefiicient of expansion. For example, in US.Patent No. 2,815,467 to Gardner, a tube with a steel body utilizes anoutwardly dished header of a material with a higher coefiicient ofthermal expansion,

Patented Jan. 10, 1967 copper, whereby a differential expansion betweenthe body and the header act to maintain the resonant frequency of thecavity constant. In U.S. Patent No. 2,880,- 357 to Snow et al., a drifttube is provided of a material with a lower coefficient of thermalexpansion than the body material, steel. As the body lengthens toincrease the inductance in the cavity resonator, the length of the drifttube increases but proportionately less so that the capacitance isdecreased in order to maintain the frequency constant.

Tubes of the types described immediately above would still have atemperature coeflicient on the order of 1,000 kilocycles per degree C.since thermal gradients would exist within the tube.

Another major disadvantage of building certain electron tubes of copperis the fact that copper is a diamagnetic material and will not shieldthe electron beam within the tube from stray magnetic fields. Therefore,stray magnetic fields are able to defocus the electron beam within sucha tube and thereby affect both the power output and frequency stabilityof the device.

In the present invention certain portions of the tube structure are madeto have certain desired properties of thermal conductivity, strength,magnetic susceptibility, and coefiicient of thermal expansion by makingthese structural portions of certain selected aggregate material. Forexample, high thermal conductivity is a generally desired property oftube structure in order to minimize unwanted thermal gradients withinthe tube. Accordingly, a good thermal conductor such as copper or silveris infiltrated into a porous metallic body having another desiredproperty such as strength alone or strength and high magneticsusceptibility. Examples of such latter body materials are tungsten andiron, respectively. The resultant aggregate will be stronger than thegood thermal conducting material and have higher thermal conductivitythan the stronger material. In the case of the iron aggregate, theaggregate will have a characteristic ferromagnetic susceptibility.

As used herein, an aggregate material is one composed of at least twoditferent materials wherein one of the materials is infiltrated into aporous body made of the other material. High thermal conductivity isdefined to mean having a thermal conductivity higher than that oftungsten. Low thermal coefficient of expansion is defined to mean havinga linear coefiicient of thermal expansion less than that of iron. Highthermal coetficient of expansion is defined to mean having a linearcoefiicient thermal expansion greater than that of iron. Low magneticsusceptibility is defined as non-ferromagnetic susceptibility. Highmagnetic susceptibility is defined as a ferromagnetic susceptibility.

According to the present invention a highly temperature stable andrugged electron discharge device is provided by constructing a portionof the device of an aggregate material having a high thermalconductivity, a low thermal coefiicient of linear expansion and lowmagnetic susceptibility. In a klystron, for example, this result isaccomplished by constructing the cavity resonator headers and drifttubes of an aggregate material having these properties such as amaterial containing substantial amounts of tungsten and copper, ormolybdenum and copper.

Where high magnetic susceptibility plays a part in the operation of thetube, a substantial portion of the tube may be made of an aggregatematerial having a high magnetic susceptibility, and a high thermalconductivity. In a klystron, for example, this second result isaccomplished by constructing the body which serves to form the sidewalls of the cavity resonator or resonators of an aggregate materialhaving these properties such as an aggregate containing copper and iron.

In a magnetron, for example, the first result is accomplished byconstructing the vane structure of the low magnetic susceptibility, highthermal conductivity, low thermal expansion material and the secondresult may be accomplished by constructing the pole pieces of the highmagnetic susceptibilty, and high thermal conductivity material. In aperiodic permanent magnetic focused traveling wave tube, for example,the pole pieces and associated spacers may form the vacuum envelope ofthe devices, the pole pieces being of the high magnetic susceptibility,high thermal conductivity aggregate material and the spacers being ofthe low magnetic susceptibility, high thermal conductivity aggregatematerial.

The object of the present invention is to provide improved electrondischarge devices having low temperature coefficients in operation.

One feature of the present invention is the provision of an electrondischarge device wherein a significant portion of the device is made ofan aggregate material having a high thermal conductivity and a lowthermal coefficient of linear expansion.

Another feature of the present invention is the provision of a novelelectron discharge device according to the last aforementioned featurewherein the aggregate material contains substantialportions of bothcopper and tungsten by weight.

Another feature of the present invention is the provision of a novelelectron discharge device wherein a significant portion of the device ismade of an aggregate material having a high magnetic susceptibility anda high thermal conductivity whereby thermal gradients within the deviceare reduced.

Another feature of the present invention is the pro-.

vision of a novel electron discharge device according to the lastaforementioned feature wherein the aggregate material forming saidsignificant portion contains substantial portions of both copper andiron by weight.

Other features and advantages of the present inven tion will become moreapparent upon a perusal of the following specification taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of an electrostatically focused four-cavityklystron amplifier embodying features of the present invention,

FIG. 2 is a side view partially in section of the structure shown inFIG. 1 taken along line 2-2 in the direction of the arrows,

FIG. 3 is a cross-sectional view of a portion of the structure shown inFIG. 2 taken along line 33 in the direction of the arrows,

FIG. 4 is a perspective view of a reflex klystron oscillator embodyingfeatures of the present invention,

FIG. 5 is a side view partially in section of the structure shown inFIG. 4 taken along line 5-5 in the direction of the arrows,

FIG. 6 is a longitudinal cross-section view of a typical form ofmulticavity klystron amplifier utilizing the present invention,

FIG. 7 is a longitudinal cross-sectional view of a periodic permanentmagnet focused type of traveling wave tube utilizing the presentinvention,

FIG. 8 is a transverse cross-section view of the tube in FIG. 7 takenalong section line 8-8, and

FIG. 9 is a longitudinal cross-section view of a magnetron tube whichutilizes the present invention.

Although the thermionic tubes shown in the drawing are specific forms ofthe klystron, magnetron and traveling wave type, it will be appreciatedfrom What follows that while such tubes realize particularly theadvantages accruing from the present invention, other tubes as well maybe equally benefited.

Referring now to FIGS. 1 and 2 an electrostatically focused, multicavityklystron amplifier made in accordance with the present inventionincludes a. central body portion 11 which is made of a unitary block ofmetal having longitudinal bore therethrough. The metal of the centralbody portion 11 will be described in greater detail below. Hollowcylindrical drift tubes 13 having circular resonator grids 14 on theends thereof are fixedly secured within the longitudinal bore 12 of thecentral body portion 11 by outwardly extending annular header members15. The walls of the drift tube 13 are parallel to the axes of thelongitudinal bore 12 and an electron beam passing therethrough.

A narrow, annular anode header 16 having a resonator grid 17 positionedin the central aperture is fixedly secured, as by brazing, in one end ofthe longitudinal bore 12 of the central body portion 11. Within theopposite end of the longitudinal bore 12 of the central body portion 11is an annular header 18 with a resonator grid 19 positioned on the endof a grid tube portion projecting axially from around the aperturetherethrough.

The anode header 16 and the first annular header 15 define an inputcavity resonator 21 within the central body portion 11. The first,second and third annular headers 15 define two buncher cavity resonators22; and the third annular header 15 and the annular header 18 define anoutput cavity resonator 23.

A beam generating assembly 24, adapted to project an electron beamaxially of the central body portion 11, is vacuum sealed, as by brazing,to the central body portion 11.

A beam collector assembly 25 is fixedly secured, as by brazing, to theend of the central body portion 11 adjacent the annular header 18. Thebeam collector assembly 25 is provided on the exterior thereof with aplurality of annular cooling fins 26 whereby the tube can be cooled.

Identical input and output waveguide assemblies 27 and 28 are secured tothe central body portion 11 and respectively communicate with the inputcavity resonator 21 and the output cavity resonator 23 through milledopenings 29 within the central body portion 11, The outwardly projectingend of each of the waveguide assemblies 27 and 28 is provided with awaveguide flange 31 which carries a wave permeable window 32 such asceramic sealed therein by a window frame member 33.

A tuner block 34 is provided in one side of the central body portion 11and provides a movable tuner diaphragm, not shown, for each each cavityresonator. Each of the tuner diaphragms is movable by means of a tuningscrew 35.

Referring now to FIG. 3 each of the resonator grids 14, 17 and 19 ismade up of an annular grid mounting ring 36 provided with a grid supportrim 37 on which a plurality of grid vanes 38 are supported. Each of thevances 38 is made up of an elongated central body portion 39 and a baseportion 41, the base portion being bent substantially with respect tothe central body portion and being fixedly secured, as by brazing, togrid suprport rim 37 with the elongated central body portion 39projecting radially inwardly of the grid ring 36.

Referring now to FIGS. 4 and 5, there is shown a reflex klystron whichembodies the present invention. This reflex klystron comprises a mainbody block 46 with a longitudinal bore extending therethrough. Anelectron gun assembly 47 and a reflector electrode assembly 48 arevacuum sealed on the body at opposite ends of the bore. The two drifttube headers or walls 49 and 51 with associated resonator grids 52 aresecured within the body bore and serve to form the cavity resonator.This reflex klystron may be tuned by means of a side wall tuner 53 inwell known manner, the output being coupled out from the cavityresonator through an iris opening in the body and through the waveguideflange 54. The main body and header materials of this reflex klystronwill be discussed below along with the materials of the klystron ofFIGS. 1 and 2.

In order to avoid' undesired temperature gradients within themulticavity or reflex klystron tubes and still avoid use of materialswith high coefficients of expansion, an-

nular headers and drift tubes which are the RP. conducting portions ofthe tube closest to the electron beam are made of an aggregate materialhaving a high thermal conductivity and a low thermal coefficient oflinear expansion.

For example, one typical aggregate material sold under the trademarkElkonite by the Mallory Metallurgical Company is an aggregate made up ofsubstantial portions of one material, for example, either copper orsilver of a high thermal conductivity and substantial portions ofanother material, for example, tungsten, having high strength and a lowthermal coefficient of linear expansion. The aggregate material is firstmade by sintering the hard component, the tungsten and then melting inthe lower melting point component, the copper or silver.

Aggregate materails may be made in other ways such as by dispersionhardening which may be accomplished by mechanical mixture, internaloxidization, or precipitation of more than two materials which arenon-soluble and non-reactive with respect to one another.

By using an aggregate material the hot portions of the tube can be madehighly thermal conductive while still very rigid. These aggregatematerials may also be selected so as to have a linear coefiicient ofexpansion approximat- TABLE I 6 body material thereby increasinginductance. The drift tube material enlarges but to a lesser extentthereby increasing the interaction gap space to decrease the capacitancethereof and thereby maintain the cavity resonator frequency constant.

The central body portion 11 of the klystron amplifier tube of FIGS. 1and 2 and the central body portion 46 of the reflex klystron of FIGS. 4and 5 is made of an aggregate material having a high thermalconductivity and a high magnetic susceptibility. With this body materialthe electron beam therein is shielded from stray magnetic fields whichwould act to defocus the beam and both reduce the power output andchange the tube operating frequency. A specific central body aggregatematerial isIndar which is a trade name for a material manufactured bythe Indar Corporation. The specific type of Indar utilized in a specifictube was one containing 23% of copper and 77% iron.

As is evident from Table II the Indar body magnetically shielded thetube from stray magnetic fields. Without the Indar body a magneticattenuator or ferrite isolator used in a system with the tube had to bepositioned at least 8" from the tube whereas when utilizing an Indarbody the ferrite isolator could be placed within 2" of the tube andactually bolted to a flange of the tube.

Another feature of the present invention is the provision of a grid ring36 made out of an aggregate material such as Elkonite. Grid rings ofsuch material provide better temperature equalization by rapidlyconducting heat from the grid and grid vanes thereby avoiding gridburnout and frequency shift due to increased beam current.

Body Material Header and Drift Tube Material Temperature CoefiicientMax. Beam Power Before Grid Burnout Steel Moly-eopper laminate Elkonite:44% copper,

56% tungsten.

Elkonite: 44% copper,

56% tungsten.

Indar: 23% copper,

77% iron.

-1,000 kc. per degree C -41.

Greater than $500 kc. per 35-41.

degree 0.

Less than $100 kc. per Probably 75 watts.

degree G.

Less than 5:50 kc. per Probably 100 watts.

degree 0.

As can be seen from Table I, tubes utilizing steel bodies 45 Specificexamples of features of this embodiment of the and steel drift tubes andheaders have an extremely high present invention are set forth in TableII below.

TABLE II Closest Tube Grid Ring Material and Frequency Shift At Spacingof No. Body Material Drift Tube Material Amount 0! Grid Vane Raise BeamVoltage of Ferrite 1,500 Volts Isolator,

inches Copper Nickel Raised 0.0 70 Megacycles 8 Nickel Raised .0l0Megacyeles 8 Nickel Raised .015 45 Megacyeles... 8 Lilo. Elkom'te Raised.015 20 Megacycles... 8 Indar: 23% copper, 77% iron e 56% do -10Megacycles 2 tungsten.

temperature coefficient. In an attempt to reduce this, Tube No. 2 wasbuilt utilizing a moly-copper laminated drift tube. One such tube had ahigh temperature coefficient greater than :500 kc. per degree C. In atube utilizing an aggregate material, specifically Elkonite of 44%copper and 56% tungsten, the temperature coefficient is typically lessthan i100 kc. per degree C.

The particular grade of Elkonite was selected as to have a high thermalconductivity and a low thermal coetficient of linear expansion.Specifically, the material was selected to have a thermal coefficient oflinear expansion somewhat less than that of the body material, steel. Inthis manner, besides providing temperature equalization, a smalltemperature compensation is provided. With the header material and drifttube material of a lower thermal As can be seen from the above table theuse of an 60 Elkonite grid ring considerably reduced the frequency shiftfor increased beam voltage.

In a magnetically focused type of electron tube device, as, for example,a magnetic focused multicavity klystron tube of the type shown in FIG.6, the utilization of an aggregate material, for example copper-iron,with a high and will not be described in detail herein except to thecoefficient of expansion than the body materials, as the tube heats upthe cavity enlarges due to the effect of the extent necessary toindicate the utilization of the present invention therein. This klystrontube,.in general, includes a cathode structure 55, an electron beamcollector structure 56, the multicavity R.F. interaction structure 57,and the electron focusing magnet structure 58.

To enhance the thermal conductivity of the tube a pair of pole pieces 63and 64, which form a part of the electron beam focusing magnetic fieldstructure 58, are made of an aggregate material having a high thermalconductivity and a high magnetic susceptibility, for example, anaggregate material which is 20-30% copper and 8070% iron.

To achieve improved thermal conductivity with this multicavity klystron,the main body wall 59, the cavity end walls or headers 61, and the drifttubes 62 are made of an aggregate material having a high thermalconductivity characteristic and a low magnetic susceptibility and acoefficient of thermal expansion approximating the thermal coefiicientof expansion of the pole pieces 63 and 64. For example, an aggregatematerial of 70% copper and 30% tungsten is suitable.

These latter two forms of aggregate material are, of course,advantageously employed in other forms of klystrons such as in, forexample, the permanent magnet focused type, an example of which is shownin US. Patent 2,915,670, issued December 1, 1959, to Louis T. Zitelli.

As an alternative embodiment of the present invention the pair ofmagnetic pole pieces 63 and 64, forming a part of the beam trajectoryconfining structure, are made of iron. In this case the main body wall59, cavity end walls 61, and the drift tubes 62 are made of an aggregatematerial having a high thermal conductivity, high strength, a lowmagnetic susceptibility, and a cofiicient of thermal expansionapproximating the thermal coefficient of expansion of the pole pieces 63and 64. A suitable aggregate for this purpose is Elkonite having 65%copper and 35% tungsten.

The present invention also finds particular utility in a traveling wavetube of the periodic permanent magnet focusing type wherein the focusingmagnetic field comprises successive periodically reversed axial magneticfields as is now well known in this field. In the embodiment shown inFIGS. 7 and 8, a plurality of spaced-apart magnet pole pieces 65 and aplurality of spacers 66 inserted between the pole pieces are made ofmaterials suitable to be brazed together to form a vacuum tight envelopefor the traveling wave tube. The pole pieces 65 and the spacers 66 mustbe of different materials since the pole pieces must have high magneticsusceptibility and the spacers have low magnetic susceptibility but itis desirable that both spacers and pole pieces have high thermalconductivity and yet be compatible with regard to their coefiicients ofthermal expansion to avoid leaks in the vacuum joints.

The traveling wave tube shown in FIGS. 7 and 8 includes a cathodeassembly 67, anode 68, the slow wave helix 69, and the electron beamcollector assembly 71. The main vacuum envelope of this traveling wavetube includes the plurality of annular pole pieces 65 and the annularspacers 66 which are brazed to the pole pieces 65. The helix 69 issupported within the longitudinal bore formed in the axial center of thepole pieces 65 and the spacers 66 by sapphire rods 72. Suitable inputand output coupling means 73 are vacuum sealed within the pole piecespacer assembly. The magnets 74 which form the periodic magnetic fieldsare formed of two C-shaped halves which clamp around the spacers andadjacent the pole pieces, these magnets being so positioned as to formthe periodically reversed magnetic fields extending between the polepieces 65 axially of the structure. A hollow cylindrical sleeve 75 issecured around the outer periphery of the permanent magnets 74 to holdthe assembly in place.

In this embodiment, the pole pieces 65 are made of an aggregate materialhaving a high thermal conductivity and a high magnetic susceptibility,for example, an aggregate material having a substantial portion of iron,for example, 23%-30% copper and 77%-70% iron. The annular spacers 66 aremade of an aggregate material having a high thermal conductivity and alow magnetic susceptibility, for example, a copper-tungsten aggregatesuch 49% copper and 51% tungsten. The coefficient of thermal expansionof these two aggregate materials is compatible and no serious problemsare encountered with leaks, misalignment, etc., due to thermal expansiondifferences between the pole pieces and the spacers during operation.

The use of this invention in a cross-field device or magnetron isexemplified in FIG. 9 which discloses, in longitudinal cross-section, atypical form of magnetron of the type more clearly shown and describedin US. patent application Serial No. 105,715 entitled, Magnetron, filedApril 26, 1961, in the name of Jerome Drexler et al. This specific formof magnetron is sold as model SFD303 by the S-F-D Laboratories of Union,New Jersey. The main body assembly of this magnetron is designated byreference numeral 81 to which there is suitably brazed the anodeassembly 82 and the cathode assembly 83 including the cylindricalcathode emitter 84. The magnetron interaction region is defined by thecylindrical space between the outer periphery of the cylindrical cathodeemitter 84 and the inner tips of a circular array of radially inwardlydirected anode vanes 85 or wave supporting structure which are carriedat their outer peripheries from the inside surface of a cylindricalanode wall 86. As is well known in this art, the spaces between adjacentvanes within the interior of the cylindrical anode wall 6 define theplurality of inner cavity resonators which interact with the electronbeam or stream of this device. The outer cavity resonator 87 is formedin the main body block 88 and is coupled to the inner resonators definedby the vanes 85 and walls 86 through coupling holes in the wall 86 inwell known manner. The output energy is extracted from the magnetron viaoutput coupling slot 89, waveguide 91, and vacuum sealed windowstructure This known form of magnetron incorporates a magnetic circuitor structure which provides a tubular shaped magnetic field extendingbetween the inner ends 93 and 94 of the two cylindrical pole pieces 95and 96, these pole pieces being coupled to a C-shaped permanent magnet(not shown) via cylindrical magnetic members 97 and 98 and 98.

In an improved form of this magnetron made in accordance with thepresent invention, the vanes 85, wall section 86, and/or external cavitywall 88 may be made of an aggregate material having a high thermalconductivity, and low magnetic susceptibility such as, for example,coppertungsten or silver tungsten. Thus the high conductivity willinsure rapid heat dissipation and the low thermal expansion will insuresmall changes in size with temperature changes.

In addition, the magnetic members 95, 96, 97, 98 and 98' may be made ofan aggregate material having a high thermal conductivity and a highmagnetic susceptibility such as, for example, an aggregate material withsubstantial portions of copper and iron.

Since many changes could be made in the above construction and manyapparently widely ditferent embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An electron discharge device comprising:

(a) means for producing an electron beam, and

(b) conductor means adjacent said electron beam producing means forconducting radio frequency wave energy,

(1) said conductor means being made of an aggregate material comprisinga porous metallic structure made of a material having a thermalcoefiicient of linear expansion less than that of iron with the pores ofsaid porous structure being infiltrated with a second metal having athermal conductivity greater than that of tungstem.

2. The electron discharge device of claim 1 wherein said aggregatematerial contains substantial portions of copper by weight.

3. The electron discharge device of claim 1 wherein said aggregatematerial contains between 30 and 70% copper by weight.

4. The electron discharge device of claim 1 wherein said aggregatematerial contains substantial portions of copper and tungsten by weight.

5. The electron discharge device of claim 4 wherein said aggregatematerial contains between 30 and 70% copper by weight and 70 and 30%tungsten by weight.

6. A resonator structure comprising:

(a) a cavity resonator adapted to pass an electron beam therethrough,

(b) means defining cavity end walls for conducting electromagneticwaves, and

(c) an interaction gap defined by a pair of drift tubes projecting frommutually opposing cavity end walls,

(d) said drift tubes and said opposing cavity end walls made of anaggregate material comprising a porous metallic structure of a firstmetal having athermal coefiicient of linear expansion less than that ofiron with the pores of said porous metallic structure infiltrated with asecond metal having a thermal conductivity greater than that oftungsten.

7. The resonator structure of claim 6 wherein said aggregate materialcontains substantial portions of copper by weight.

8. The resonator structure of claim 6 wherein said aggregate materialcontains substantial portions of copper and tungsten by weight.

9. A high frequency tube apparatus including:

(a) a main body,

(b) means for producing an electron beam within said body,

(c) said body having at least one cavity resonator formed therein in thebeam path for electromagnetic interaction with the electron beam,

(d) said main body forming the side walls of said cavity resonator,

(e) header members forming the end walls of said cavity resonator andadapted to pass an electron beam therethrough,

(f) said header members made of an aggregate material comprising aporous metallic structure made of a first metal having a-thermalcoefficient of linear expansion less than that of iron with the pores ofsaid metallic body infiltrated with a second metal having a thermalconductivity greater than that of tungsten.

10. The tube apparatus of claim 9 wherein said aggregate materialcontains substantial portions of copper by weight.

11. The tube apparatus of claim 7 wherein said aggregate materialcontains substantial portions of copper and tungsten by weight.

12. A high frequency tube apparatus including:

(a) a main body,

(b) means for producing an electron beam within said main body toproduce radio frequency energy,

(c) conductor means adjacent said electron beam producing means forconducting radio frequency wave energy,

((1) said main body being made of an aggregate material comprising aporous metallic structure made of a material having a ferromagneticsusceptibility with the pores of said metallic structure infiltratedwith a second metal having a thermal conductivity greater than that oftungsten.

13. The tube apparatus of claim 12 wherein said aggregate materialcontains substantial portions of copper by weight.

14. The tube apparatus of claim 12 wherein said aggregate materialcontains substantial portions of copper and iron by weight.

15. The tube apparatus according to claim 12 wherein said aggregatematerial contains between 15 and 40% copper by weight and between and60% iron by weight.

16. A high frequency tube apparatus including:

(a) a main body,

(b) means for producing an electron beam within said body,

(0) said body having at least one cavity resonator formed therein in thebeam path for electromagnetic interaction with the electron beam,

(d) said means body forming the side walls of said cavity resonator andmade of an aggregate material comprising a porous metallic structuremade of a material having ferromagnetic susceptibility with the pores ofsaid metallic structure being infiltrated with a second metal having athermal conductivity greater than that of tungsten,

(e) header members forming the end walls of said cavity resonator andadapted to pass the electron beam therethrough for electromagneticinteraction at a gap therebetween,

(f) said header members made of an aggregate material comprising aporous metallic structure of a metal having a thermal coeflicient ofexpansion less than that of iron with the pores of said porous structurebeing infiltrated with a second metal having a thermal conductivitygreater than that of tungsten.

17. The high frequency tube apparatus of claim 16 wherein,

(a) said main body is made of an aggregate material containingsubstantial portions of copper and iron by weight and (b) said headermembers are made of an aggregate material containing substantialportions of copper and tungsten by weight.

18. A grid structure comprising:

(a) an annular grid mounting ring provided with a grid support rim,

(b) a plurality of grid vanes supported on said grid support rim.

(1) each of said vanes provided with an elongated central body portionand a base portion at the end of said central body portion, and

(2) said base portion of each of said vanes secured to said grid supportrim,

(c) and said mounting ring being made of an aggregate materialcomprising a porous metallic structure made of a metal having anonferromagnetic susceptibility with the pores of said metallicstructure infiltrated with second metal having a thermal conductivitygreater than that of tungsten.

19. The grid structure of claim 18 wherein said mounting ring is made ofsubstantial portions of copper.

20. The apparatus according to claim 19 wherein said aggregate mountingring contains substantial proportions of a metal selected from the groupconsisting of tungsten and molybdenum.

21. A high frequency tube apparatus of the magnetic focus typecomprising in combination:

(a) a main body forming a portion of the vacuum envelope of said tubeapparatus,

(b) means for producing an electron beam in said body,

(c) said body having at least one cavity resonator formed therein in thebeam path for electromagnetic interaction with the electron beampassable therethrough,

(d) header members forming the end walls of said cavity resonator andadapted to pass the electron beam therethrough for electromagneticinteraction at a gap within said cavity resonator,

(e) magnetic pole members forming another portion of said body andextending on either side of said cavity resonator for operating withexternal magnetic means to focus the electron beam within said cavityresonator, said pole pieces being of an aggregate material comprising aporous metallic structure made of a ferromagnetic susceptibility withthe pores of said metallic structure infiltrated with a second metalhaving a thermal conductivity greater than that of tungsten,

(f) said main body forming the side walls of said cavity resonator, saidmain body and said header members being made of an aggregate materialcomprising a porous metallic structure made of a material having anonferromagnetic susceptibility with the pores of said metallicstructure infiltrated with a second metal having a thermal conductivitygreater than that of tungsten.

22. A high frequency tube apparatus as claimed in claim 21 wherein theaggregate material of said body and header material has a thermalcoefiicient of expansion within 30% of the thermal coefficient ofexpansion of said pole members.

23. Tube apparatus of claim 21 wherein said aggregate material of thebody and header members contains substantial portions of copper andtungsten by weight.

24. A high frequency tube apparatus according to claim 21 wherein theaggregate material of said pole comprises a substantial portion ofcopper and iron.

25. An electron beam tube of the traveling wave tube type comprisingmeans for producing an electron beam therein,

(a) a slow wave structure for interaction with said electron beam,

(b) a collector for collecting said electron beam,

() said electron tube including a magnetic focusing structure includinga plurality of annular pole pieces positioned along the length of theelectron beam and a plurality of spacer members located between the polepiece members and serving to space said pole pieces one from another,

(d) and said pole piece members being of an aggregate materialcomprising a porous metallic structure made of a metal having aferromagnetic susceptibility with the pores of said metallic structurebeing infiltrated with a second metal having a thermal conductivitygreater than that of tungsten.

26. The traveling wave tube apparatus as claimed in claim 25 whereinsaid spacer members are made of an aggregate material comprising aporous metallic structure made of a nonferromagnetic susceptibilitymetal with the pores of said metallic structure being infiltrated with asecond metal having a thermal conductivity greater than that oftungsten.

27. The apparatus according to claim 26 wherein said spacer members havea thermal coefiicient of expansion within 30% of the thermal coefficientof expansion of said pole piece members.

28. The traveling wave tube apparatus as claimed in claim 26 wherein theaggregate material of said pole pieces comprises substantial portions ofcopper and iron and wherein said aggregate material of said spacerscomprises substantial portions of copper and tungsten.

29. High frequency tube apparatus of the crossed field type comprising:

(a) a main body forming a portion of a vacuum envelope of said tubeapparatus,

(b) means for producing a stream of electrons in said main body,

(c) said main body having a wave supporting structure therein in waveenergy exchanging relationship with said stream of electrons,

(d) magnetic structure formed within said body for directing a magneticfield having a substantial component thereof normal to the meandirection of travel of the electron stream,

(e) said main body being made of an aggregate material comprising aporous metallic structure made of a nonferromagnetic material with thepores of said metallic structure being infiltrated with a second metalhaving a thermal conductivity greater than that of tungsten,

(f) and said magnetic structure being made of an aggregate materialcomprising a porous metallic structure made of a material having aferromagnetic susceptibility with the pores of said structure beinginfiltrated with a second metal having a thermal conductivity greaterthan that of tungsten.

30. The apparatus according to claim 29 wherein said aggregate materialof said main body and said magnetic structure contains a substantialproportion of copper by weight.

31. The apparatus according to claim 29 wherein said aggregate materialof said main body and said wave supporting structure contains asubstantial proportion of copper and tungsten by weight.

32. The apparatus according to claim 29 wherein said material of saidmagnetic structure contains a substantial proportion by weight of copperand iron.

33. A high frequency tube apparatus employing a magnetically confinedelectron stream comprising:

(a) a main body forming a portion of a vacuum envelope of said tubeapparatus,

(b) means for producing a stream of electrons in said main body,

(c) said main body having a wave supporting structure therein in waveenergy exchanging relationship with said stream of electrons,

(d) magnetic structure formed within said body for directing a magneticfield into the stream of electrons for confining the stream of electronsto a desired trajectory,

(c) said magnetic structure being made of iron,

(f) and said main body being made of an aggregate material comprising aporous metallic structure made of a metal having a nonferromagneticsusceptibility with the pores of said metallic structure infiltratedwith a second metal having a thermal conductivity greater than that oftungsten.

34. The apparatus according to claim 33 wherein said aggregate materialof said body has a thermal coefficient of expansion within 30% of thethermal coefficient of expansion of said iron magnetic structure.

References Cited by the Examiner Microwave Magnetrons, Collins, M.I.T.Radiation Laboratory Series, McGraw-Hill, N.Y., 1948 (pages 649 and 650relied on).

HERMAN KARL SAALBACH, Primary Examiner.

R. D. COHN, Assistant Examiner.

1. AN ELECTRON DISCHARGE DEVICE COMPRISING: (A) MEANS FOR CONDUCTINGRADIO FREQUENCY WAVE (B) CONDUCTOR MEANS ADJACENT SAID ELECTRON BEAMPRODUCING MEANS FOR CONDUCTING RADIO FREQUENCY WAVE ENERGY, (1) SAIDCONDUCTOR MEANS BEING MADE OF AN AGGREGATE MATERIAL COMPRISING A POROUSMETALLIC STRUCTURE MADE OF A MATERIAL HAVING A THERMAL COEFFICIENT OFLINEAR EXPANSION LESS THAN THAT OF IRON WITH THE PORES OF SAID POROUSSTRUCTURE BEING INFILTRATED WITH A SECOND METAL HAVING A THERMALCONDUCTIVITY GREATER THAN THAT OF TUNGSTEN.